Many more, including Philadelphia Fire Department paramedics, have discussed doing it.
At its most basic, inducing hypothermia is easy (pack resuscitated patient in ice or infuse chilled saline) and cheap (buy coolers for same). There is no clear evidence that starting before arrival at the emergency room helps - but there also are few downsides.
More than 300,000 Americans a year go into sudden cardiac arrest - a complete cessation of activity that can result from a massive heart attack and other conditions - and the vast majority never make it to the hospital.
Minutes after the heart stops beating, the brain begins to die from lack of oxygen. Manual chest compressions can keep some blood flowing, but unless the heart is restarted quickly, the patient will not survive. When circulation is restored, however, inflammation and other reactions usually cause permanent neurological damage.
Therapeutic hypothermia is the only way to prevent this, medical experts said, and how it works is not fully understood. Over several hours, a comatose patient is cooled to between 89.6 and 93.2 degrees Fahrenheit and held 12 to 24 hours; then the body is gradually warmed.
It is used mainly on adults whose hearts were restarted quickly and who were functioning normally beforehand - perhaps 10 percent of all cardiac-arrest patients would be candidates, two experts estimated.
Within that select group, research has shown that inducing hypothermia in the ER roughly doubles chances of survival - from 22 percent to 50 percent, for example, in a University of Pennsylvania study published last year.
An Inquirer survey of more than 50 hospitals in the region determined that most recently began using the procedure or are about to start.
Still, there are plenty of questions, especially about the expansion to ambulances.
Chief among them: Does cooling en route do any good?
Research published last month in Circulation found nearly identical outcomes for patients whose hypothermia began in the ambulance and continued in the hospital vs. those started in the ER.
Perhaps real-world implementation of a good idea has unintended consequences such as interrupting the cooling process upon arrival at the hospital, Lance Becker, an emergency-medicine doctor at Penn, wrote in an accompanying editorial.
There is a widespread belief, however, that the benefits of "pre-hospital" cooling haven't shown up in the research statistics because the ambulance ride is only a short part of a process that takes several hours.
"Does the 15 minutes make a difference? The jury is still out on that," said Stephen Trzeciak, an emergency-medicine physician at Cooper University Hospital, who tells other ERs how to pack resuscitated patients in ice for transport to Camden. "But you certainly can kick-start the process."
Another question is whether patient volume matters.
"We feel like you need to do this fairly often to be good at it," said J. Brent Myers, EMS director for Wake County, N.C., which pioneered paramedics' use of therapeutic hypothermia four years ago.
The hospitals and centralized EMS in Wake County, which includes Raleigh, planned the move together. Rather than installing coolers in all 50 ambulances, they went with 10 vehicles staffed by supervisors, who respond to all cardiac-arrest calls. Two of the county's 11 hospitals agreed to induce hypothermia, and they share all of the 100 or so patients a year that are started in transit.
In the Philadelphia region, only the biggest medical centers induce hypothermia in more than a few dozen patients a year. They include Christiana and Wilmington hospitals in Delaware, which say they were among the first in the nation to use the technique and have induced several hundred patients since 2003. The centralized EMS system in New Castle County, where the sibling hospitals are located, trained its paramedics in March 2009 and has cooled 84 patients in transit.
But those numbers are exceptions. Virtua Marlton has induced 11 patients in the ER since starting a year ago. Holy Redeemer has had one since July 2009.
Local paramedics get even fewer cases. Delaware County Memorial Hospital EMS has had seven since November. Longwood has been waiting for its first patient since April 2009; Mercy Fitzgerald's paramedics are still waiting, too.
As long as appropriate guidelines are in place, the numbers don't bother Ben Usatch, a Lankenau ER doctor who also serves as regional medical director for Montgomery County, where he said all 20 or so EMS squads are interested in cooling. "This is not as technically rigorous a type of procedure," he said, as complex surgeries for which research has shown high volume is better.
Still, experts from Penn and elsewhere proposed earlier this year that regional systems of care for cardiac arrest be formed nationwide in much the same way that trauma centers are now designated to receive trauma patients. That could take years.
Derek L. Isenberg, who completed his residency in emergency medicine at Mercy Fitzgerald Hospital two years ago, became intrigued by therapeutic hypothermia during a fellowship at Yale.
When Isenberg returned to Mercy as an attending physician in May, the ER was already doing it. His responsibilities included the fire company ambulances that Mercy staffs, and he quickly prepared to expand their capabilities.
His first challenge was how to physically cool patients in the vehicle. While hospitals use sophisticated, heavy equipment, paramedics just place ice around or chilled saline into the body. Both require a refrigerator. Mercy's ambulances didn't have them.
So Isenberg bought Igloo coolers designed for six-packs and tested their ability to maintain temperature over 10 days. It worked.
With five coolers, saline, and a case of ice packs, all eight towns were covered for $250. Isenberg led a one-hour training as part of regular continuing education. "The paramedics infuse the chilled saline just as they would any other saline," he said.
"It is pretty unscientific," said Bob Higgins, program director for PennSTAR, which began inducing in helicopters when flying cardiac-arrest patients to Penn a year ago. "We get a bunch of crushed ice, usually from the sending facility."
The American Heart Association issues influential guidelines for emergency cardiovascular care every five years. It included hypothermia for the first time in 2005, as a possible in-hospital treatment in limited circumstances. The new guidelines, due out next month, are widely expected to strengthen or expand the recommendations.
"You are going to see a big scramble in the next six months for physicians and nurses to get this in their hospitals," predicted Eugene Vallely, a critical-care nurse and unofficial hypothermia coordinator at Doylestown Hospital who spreads the word by inviting paramedics to meet every patient who survives.
Linda Jacobi, 54, has no idea why she survived a massive heart attack and cardiac arrest last October.
Most likely it was a combination of things: Her husband heard her hit the floor in their New London Township home, called 911, and immediately started CPR. A Southern Chester County EMS paramedic lived close by and arrived within minutes. Hypothermia was induced in the ambulance - the squad's second patient. Luck undoubtedly played a role.
She joined a reunion with the squad three weeks later.
"Thanking them seemed insignificant," Jacobi said. "How do you thank someone for giving you a second life?"
Contact staff writer Don Sapatkin at 215-854-2617 or firstname.lastname@example.org.